High-frequency relay employing an electron discharge device



Fb.10,1948. H TM N HIGH-FREQUENCY RELAY EMPLOYING AN ELECTRON DISCHARGEDEVICE 5 Sheets-Sheet 1 Filed Dec. 20, 1941 INSULA TION INSULATION //vVENTOR By P. L HARTMAN (7W, W4

A m; v

Feb. 10, 1948.

P. 1.. HARTMAN HIGH-FREQUENCY RELAY EMPLIOYING AN ELECTRON DISCHARGEDEVICE Filed Dec. 20, 1941 5 She'efs-Sheet 2 OUTPU INPUT-rnv VENTOR P.L.HARTMAN WM v A TTORNE Y Feb. 10, 1948., HARTMAN 2,435,585

G AN ELECTRON DISCHARGE DEVICE HIGH-FREQUENCY RELAY EMPLOYIN 1941 5Sheets-Sheet 5 Filed Dec. 20

IN I/ENTOR P. L. HA RTMAN 'A TTORNEY Feb. 10, 1948. HARTMAN 2,435,585

HIGH-FREQUENCY RELAY EMPLOYING AN ELECTRON DISCHARGE DEVICE Filed'nec.20, 1941 5 Sheets-Sheet 4 //v VENTOR P. L HA R TMA N J/TMMWM A TTOR/VEYFeb. 10, 1948. P, L. QARTMAN HIGH FREQUENCY 'RELAY EMPLOYING AN ELECTRONDISCHARGE DEVICE Filed Dec.

20, 1941. 4 5 Sheets-Sheet 5 FIG. 7

INVENTOR P.L.HARTMAN OUTPU A TTORNEY Patented Feb. 1Q, 1948HIGH-FREQUENCY RELAY EMPLOYING AN ELECTRON DISCHARGE DEVICE Paul L.Hartman, Bell Telephone New York, N. Y., assignor to Laboratories,Incorporated,

New York, N. Y., a corporation of New York Application December 20,1941, Serial No. 423,788

4 Claims.

This invention relates to systems employing electron discharge devicesand particularly to the design and operation of such systems for use atultra-high frequencies.

An object of the invention is to extend to still higher frequencies theusefulness of electron discharge devices designed for high frequencyoporation, by using specially adapted connecting circuits and modes ofoperation.

A feature of the invention is the use of coaxial transmission lines forinput and output connections to the electrodes of the electron dischargedevice in a number of arrangements particularly adapted for operation ina wide range of frequencies including the centimeter wave-length range.

Another feature is the use of a, reflecting or retarding potential toeffect a process of velocity sorting of the electrons in a velocityvaried electron stream emplcying electrode structures of more or lessconventional type.

Other objects and features are brought out in the following descriptionwith reference to the accompanying drawings, while the scope of theinvention is defined in the appended claims.

In the drawings:

Fig. 1 is a perspective view, partly broken away, of an embodiment ofthe invention employing a double-ended vacuum tube electron dischargedevice enclosed in a coaxial transmission line system;

Fig. 2 is a schematic diagram of suitable circuit connections for thearrangement of Fig. 1;

Fig. 3 is an elevational. view of another form of a vacuum tube suitablefor use with the inven tion;

Fig. 4 is partial plan view of the structure illustrated in Fig. 3;

Fig. 5 is a, fragmentary view showing details of construction of thestructure illustrated in Figs. 3 and 4;

Fig. 6 shows, partly in section and partly schematically, an amplifyingsystem employing the electron discharge device of Figs. 2-, t and 5;

Fig. 7 is a perspective view, partly broken away,

of another embodiment of the invention;

Fig. 8 is a cross-sectional view of a portion of the structure of Fig.7;

Fig. 9 is a schematic diagram of circuit connections for the arrangementof Figs. 7 and 8;

Fig. 10 is a perspective view, partly broken away, of still anotherembodiment; and

Fig. 11 is a crcss-sectional view of a portion of the structure of Fi1%).

Referring to Fig. 1, it] represents the envelope of an electrondischarge device thereby to a, terminal or vacuum tube designed for highfrequency operation, having a central flange I20 and. having grid andplate leads ii and i2, respectively, coming out from opposite ends inknown manner for the purpose of reducing the interelectrode capacity.The tube may, for example, be of the type disclosed in United StatesPatent 2,017,549, issued October 15, 1935, to B. Salzberg. An inputcoaxial line with an inner conductor l3, I3 and an outer conductor I4 isprovided having a tuning stub terminated by a conductive piston l5carrying a bushing It to insulate it from the inner conductor portion I3and arranged for axial adjustment. The bushing l5 may be of mica orother suitable insulating material. The piston l5 forms ashort-circuiting termination for the stub line at high frequency and maybe provided with any suitable mechanical means The conductor i3 isconnected through an insulating joint or blocking condenser structurel3" with conductor l3 and the latter conductor is conductively connectedwith the lead H. The sheath M has an enlarged end [6 surrounding thelower part of the envelope l0 and terminating in a flange H. A similarcoaxial line is provided for the output circuit with inner conductorsi8, i8 and a sheath IS. The line has a tuning stub with an adjustablepiston 20 having an insulating bushing 20' surrounding the conductor it.The inner conductor I8 is connected to the conductor i8 through ablocking condenser l8" and the conductor I8 is conductively connectedwith the lead l2. The sheath I9 has an enlarged portion 2| terminatingin a flange 22 opposite the flange ll of the input line. Between theflanges l1 and 22 are clamped a plurality of conductive rings orapertured plates 23 separated by insulating layers 24. There are aplurality of leads 25 protruding from the flange I20 of the envelope H!which serve for connections to a filament, a cathode and one or moreauxiliary grids within the envelope. Each lead 25 is connected to a,different plate 23 and or lug 23' attached to the plate. The assembly23, 24, together with the flanges l1 and 22, forms a stack or pluralityof by-pass condensers effectively connecting together the filament,cathode and auxiliary grids for high frequency currents and renderingthese electrodes essentially equipotential.

Fig. 2 shows in schematic form the arrangement of Fig. 1 and associatedcircuits. The envelope Iii is assumed to contain a cathode 25, a. heater26', a plurality of grids 21, 28 and 23 and an anode 30. The inputcoaxial line is confor its manipulation.

'sponding to changes in the pressed high frequency wave. When using thesystem as a detector the output circuit may be of regenerativeamplification output may be received in a suitable device such potentialis adjusted 3 nected between the grid 21 and the cathode 26, to theformer through the blocking condenser 3". One terminal of the outputcoaxial line is connected to the anode 38 through the blocking condenseri8" and the other through a blocking condenser M6 to the grid 29. The.tube is energiZe-d by a source of direct electromotive force. shown as abattery 33 impressed between the cathode 26 and the anode Bil. The grids2i and 29 are connected to intermediate points of the source 33, thegrid 29 being at -the higher potential. The graduated potentialdifferences inipressed upon the electrodes .26, 2'i,-29 and 39 by thesource 33 serve to accelerate electrons lea'v-- ing the cathode 26 andto form them'into anelectron beam falling upon the anode 353.

the grid 28 by connecting it, for example, to'a potent ometer H3. Thereflecting or retarding field of the electrode 28 serves to effect avelocity sorting of the electrons-in the beam. Electrons arriving in theneighborhood of electrode 28 with suii-"icient velocity will continue onto the anode 36. Other electrons, having smaller velocities will bedrawn to the grid 28, and others slower still: will beturned back towardthe cathode and may be collected by the grid 2?.

In the operation. of the system of. Fig. 2, a high frequency inputwaveis applied to the grid 21 by means of the input coaxial line, whichimpresses a velocity variation upon the electrons as they pass betweenthe cathode'26 andthe grid 2?. Consequently, some of the electrons gainvelocity A. reflecting or retarding voltage is impressed upon -ciency ofa detector, the device operatingregeneratively as above-mentioned.

Figs- 3, 4', 5, and 6 illustrate another form of electron dischargedevice which is particularly well adapted for use. in systems accordingto the presentinvention. The discharge device is of the type more fullydescribed, and claimed per se, in my copending application Serial No.395,948, filed May 31, 1941, Patent No. 2,403,444, July 9, 1946,assigned to the assignee of the present application. The dischargedevice comprises an indirectly heated equipotential cathode including acylindrical metallic sleeve to fitted in apertures in a pair of shieldplates 55.! and coated on its outer surface with a thermionic material,the sleeve enclosing a. heater filament 75, shown schematically in Fig6. Heating current may be supplied to the filament 75 through conductors4| extending through apertures in the sleeve 49, as shown in Fig. 5, andthrough the base plate 5|,

the conductors 4| being sealed to the base plate in suificient amount topenetrate the retarding field and reach the anode 30, therebyconstituting an output current. By proper choice of the spacing betweenthe grid 21 and cathode 2B and between the grids 21 and 28' and byproper adjustmentof the potentials, the electron transit time may beadjusted, for example, in terms of the periodic cycle of the impressedwave, to oneha-lf cycle between the cathode 26' and the grid 21 andone-quarter cycle between the grids 21 and 28. between grids 21 and 28somewhat different from that between the first two suppress electronoscillations of the type present in oscillators of the Barkhausen type.An electron executing that type of oscillation will tend to swing in anexcursion symmetrical with re spect to gridZl' which will take it beyondgrid 28 into the strong accelerating fields of grid 29 and anode 30, tobe drawn to the anode. Wit-h suitable arrangements a good velocityvariation is effected as the electrons move from the oathode to the grid27 and velocity sorting occurs between the grids 21 and2'9. Theelectrons passing grid 29 are then accelerated toward the anode 30. g l

The system of. Figs. 1 and 2 may be adjusted for operation either as anamplifier, an oscillator or a detector. By using a retarding potentialsuch that substantially all the electrons are turned back in the absenceof any high frequency excitations, the system acts as a detector,reamplitude of an imtuned to the input frequency'to take advantage andthe detected as a telephone receiver 36.

Amplification is secured when the retarding to reduce the current,preferably to substantially half of its maximum value,

It is desirable tO'Ihake the transit time electrodes in order to r byinsulating beads 52; The cathode is encompassed by a cage type controlgrid l5 coaxial therewith, the grid comprising a pair of metalliccollars 42 fitted in depressions or apertures in thin insulating plates43, for example of mica, secured to the shield plates 50, and aplurality of equally spaced parallel wires. 44 secured at" their ends tothe collars 42. The control grid 76 is provided at opposite ends withtapering, strip leading-in conductors 45 which extend midway between apair of shields 53 and 54 and are connected to conductors 46 joined totwo eyelets 55.

The control grid is encompassed in turn by a screen grid 1'! whichcomprises a plurality of metallic laminations 4'! apertured adjacent oneend to provide circular openings coaxial with the control grid andmaintained in parallel relation by metallic spacers 48.v The screen gridTl abuts the insulating members 43 and is seated upon a thin insulatingmember 43, such as a mica plate, upon the base plate 5i, so that thescreen is at radio frequency cathode or ground potential. screen gridmay be established through a leadingin conductor 56 extending throughthe base plate 5| and hermetically sealed thereto by an insulating bead51.

Mounted in cooperative relation with the oathode 49 and control grid 16is an anode, designated generally by the reference numeral 58, composedof two similar halves having joined flanges 62, laterally extendinggenerally triangular portions 63. and intermediate arcuate portions 54which together define a substantially semicircular electron receivingportion uniformly spaced from and parallel to the cathode and controlgrid. The laterally extending portions 53 are provided at their outerends with sockets 65 in which leading-in conductors 66 are secured.

The enclosure of the electron discharge device is completed by anair-tight member 67, which may be of glass, hermetically sealed at itsedge to a flanged metallic ring 58, the flange of which is hermeticallyjoined, as by welding, to the base plate 5!. The base plate 5| hasjoined thereto a total of four metallic eyelets 55 through which Directcurrent connection to the.

pass certain of the leading-in conductors for the electrodes of thedevice.

Fig. 6 shows, partly insection and partly schematically, the device ofFigs. 3, 4 and 5 connected in an amplifying system. A source lZil ofwaves to be amplified, for example, ultra-high frequency waves, isconnected between the outer conductor 59 and inner conductor i l of acoaxial line serving as the input line. Another coaxial line serving asthe output line with an outer conductor [2| and an inner conductor IE2is connected to a utilization device of any suitable kind, repre sentedhere by a resistor E28. The input line has a tuning stub I24 in which isfittted a piston !25 of annular form adjustable axially by any suitablemeans and manipulated, for example, by a knob I26. The grid leading-inconductor 45 is taken out through a quartz insulator 12 in one of theeyelets 5d, the insulator being sealed to the conductor 55 and to theeyelet by quantities of silver 13. The fabrication of the seal isdescribed in more detail in my copeliding application, supra. Theconductor #35 is insulated from the inner conductor "M by a collar 14'',which may be of mica, for example. The conductor 45 continues inside theconductor 14 in the form of an insulated wire 14 and emerges at the endof the tuning stub where it connects to a suitable tap on the battery33.

The opposite end of the control grid is connected to the inner conductorof a tuning coaxial line through another of the eyelets 55, Similartuning coaxial lines are provided at both ends of the anode 58, one ofwhich contains an insulated lead connecting the anode to positiveterminal of the battery 33. The other anode tuning line connects withthe resistor I23. The lead 55 from the screen grid 11 connects to avariable point of a potentiometer 58 by means of which the screen gridpotential may be adjusted to a small positive or negative value suitablefor best operation.

In accordance with one mode of operation 0 the system of Fig. 6, theindividual electrons emerging from the cathode All are variouslyaccelerated by the impressed alternating field between the cathode andthe control grid accord ing to the phase of the field to which they areexposed. The slower electrons are turned back by the screen grid whichis at substantially the cathode potential. The faster electrons aredrawn to the anode. As in the case of the system of Figs. 1 and 2,amplification is best ob tained by an adjustment or the biasingpotentials such that about half the maximum current reaches the anode inthe absence of impressed alternating input potentials. Then the inputwave will cause fluctuations above and below the initial anode currentto produce a replica in the anode circuit.

In accordance with another mode of operation of the system of Fig. 6,the retarding potential upon the screen grid may be reduced enough to.

permit substantially all the emitted electrons to proceed to the anode.In this case a drifting action is effected in which the faster electronsovertake the slower ones to form groups or bunches of electrons whichgive rise to a pulsating anode current. Either mode of operation isfacilitated by the parallel plate construction of the screen grid.

Fig, 7 shows an arrangement operating on the principle of electronvelocity filtering, and suitable for insertion between tuned coaxialtransmission lines. An input section of line with an inner conductor 88and an outer conductor 8i is shown entering an insulating evacuatedenvelope 82 through suitable seals. The inner conductor 88 is preferablyhollow, at least at the end within the envelope and merges into a flutedcathode 8% shown more clearly in Fig. 8, in cross section viewed fromthe line 8' in Fig. 7. A section or the outer conductor 8| within theenvelope and opposite the cathode 84 is provided with a plurality ofaxial slots 85, one opposite the center of each concave portion of thecathode. An insulated heating element 86 is supported in an axialposition within the cathode 84 in any suitable manner and the ends ofthe element 86 are brought out through the conductors 80, 88 and throughthe envelope 82 in any suitable manner, not shown, the connections tothe element 86 being insulated from the conductors 88, 8|.

Opposite each of the slots is suitably mounted a pair of curvedsubstantially parallel plates 81, 88, which may be of circularcylindrical shape and preferably have a'r'nean circular arc ofapproximately 127 degrees.

The assembly of plates 81, 88 is enclosed in a hollow conductivecorrugated tube 89 as shown, the outer opening between each individualpair of plates 81, 88 being close to one of the corrugations in the tube89.

At the end of the envelope 82 opposite the input transmission line 80,8| there is sealed an output coaxial transmission line with innerconductor 98 and outer conductor 9 l. The inner conductor 90 terminatesinside the envelope or where it is conductively connected to theassembly comprising the plurality of plates 8?, 88 through biasing meansas hereinafter more fully described, The outer conductor 9| flares tomerge with the tube 89 but is insulated therefrom by a suitable couplingsection 91.

In the operation of the system of Figs. 7 and 8 the element 88, whenheated, serves to heat the cathode 84 and by virtue of the shape of thefluted surface of the cathode 84 a sheet of elec trons is emitted andfocussed to pass through the slot 85, there being a sheet of electronsfor each slot 85.

The operation of the various elements of the tube will be more readilyunderstood from Fig. 9 which is a schematic diagram including theconnecting circuits, The anode element to is placed at a relatively highpositive potential with respect to the cathode 84 by means of thecombined voltages of batteries 52, Q3, and preferably through aninductive element 94', which latter, at ultra-high frequencies, maycomprise merely the inductance of a short length of lead. The plates Bl,88 are biased to slightly different potentials with respect to thejunction point between the batteries 92 and 93 by means of bat teries 94and 95, respectively, or by other suitable means. The potentialdifference between the cathode 84 and the grid 85 is adjusted to a smallpositive or negative value by means of a potentiometer across thebattery 36. It will be understood that any or all of the batteries shownmay be replaced by any suitable sources of direct electromotive force.Electrodes 85, 8'5 and so are preferably connected together for highfrequen cies by means of built-in by-pass condensers.

A high frequency wave to be amplified may be impressed upon the inputtransmission line 88, 8'! by a suitable source 98 and the outputtransmission line may be connected with a load represented by a resistor99. The input line and the sesame associated cathode and heater leadsare represented in Fig. 9 by an equivalent transformer I30 tuned by acondenser I3I. The source 98 will set up a pulsating potentialdifference between the cathode 04 and the grid 85 thereby impressing asuccession of velocity variations upon the electrons in the streamemerging from the cathode. Depending upon the fixed potential differencebetween the plates 81 and 88 the electrons will follow various curvedpaths in the space between the plates under the influence of, thetransverse electric field therebetween. Within a certain narrow range ofvelocities all the electrons entering the space between the plates withsuch velocities will emerge at the, far end without striking either ofthe plates and be drawn to the anode B9. Electrons having velocitiesbelow the critical range will strike the plate, 01 and electrons havingvelocities greater will strike the plate 80. Hence, if the system isadjusted so that the potential differences impressed by the input wavesare such as to vary the electron velocities through the critical range,the electron current to the anode 09 will be varied, thereby generatinga high frequency current in the output circuit. It will be evident thatthe high frequency component of the output current will be transmittedto the load through the output transmission line 00, 0!. It will beevident that the system may be adjusted to give either one or two outputpulses for each cycle of the input wave, thereby giving eitheramplification or frequency doubling, the latter adjustment being similarto the adjustment for a detector.

The arrangement of Figs. '7 and 8 is claimed in my copending applicationSerial No. 516,290, filed December 30, 1943, assigned to the assignee ofthe present application.

An alternative arrangement operating on the same principle as the systemof Figs. 7,.8 and 9 is shown in Figs. 10 and 11. The arrangement of theelements is seen most readily in Fig. 11, showing a section on the lineII in Fig. 10. The cathode IEiI has but two active surfaces both ofwhich are fluted as are the surfaces of the oathode 84 in Fig. 8. A pairof focussing electrodes I02 and I03 are provided between the cathode [0iand enlargements I04 and I05, respectively, of a pair of concentriccylinders I06, I01. The nonenlarged portions of the cylinders I06, I01form a pair of arcuate velocity filtering elements, one on either sideof the cathode IOI. The are subtended by each filtering element is againpreferably approximately 127 degrees. A common anode I00 is providedenclosed by enlargements I09 and I I0,respectively, of the cylinders I00and I01. A heating element II I is provided within the hollow interiorof the cathode IOI, the ends of the element III being suitably broughtout through a hollow inner conductor H2 forming part of. an inputcoaxial line, shown at the right of Fig. 10 and having an outerconductor H3. The inner conductor H2 is conductively connected to thecathode IilI. The outer conductor II 3 flares to merge into theenlargement I04. The anode I08 merges with the inner conductor I I4 ofan output coaxial line of which the outer conductor H5 is flared tomerge with the enlargement I00. Any suitable means may be provided tosupport the coaxial lines and the various electrodes and the assemblymay be suitably enclosed by a vacuumtight insulating envelope H0, thelatter serving incidentally as a support. For example, the outerconductor I13, enlargement I 04, cylinder I06, enlargement I 00 andouter conductor I I5 may be integral and supported by the envelope surerounding the conductor II5 atthe left and the conductor H3 at the right.The cathode IOI, electrodes, I02 and I03, and cylinder I01 may besupported by the conductor II2 properly sealed into the envelope, andthe leads from the heater III, and from the other electrodes comprisingmembers IOI, I02, I03, I01 may be brought out through the hollowinterior of conductor H2. The anode I08 may be supported by theconductor I M properly sealed into the envelope. Builtin by-passcondensers are preferably provided connecting elements I02, I03, I05,I06 and I0! together for high frequencies.

In the operation of the system of Figs. 10 and 11, with suitable biasingpotentials applied, a sheet of electrons emerges from either side of thecathode IOI, passes through the slots in the focussing electrodes I02and I03 and enters the space between the cylinders I00 and I01. In thecritical range of electron velocities the sheet of electrons reaches theanode I00. At other electron velocities the electrons are intercepted byone or the other of the cylinders I06 and I01, as described inconnection with Fig. 9.

What, is claimed is:

1. A retarding otential system for detecting velocity variations in astream of negatively charged particles comprising a space dischargedevice having a pair of grids located one beyond the other in the spaceintermediate between a cathode and an anode, the first of said grids inorder beyond said cathode being adapted to be biased at a positivepotential with respect to said cathode and the second of said gridsbeing adapt-- ed to be biased in the neighborhood of the oathodepotential and thus to provide a retarding electric field, the spacingbetween said first and second grids being materially less than thespacing between said cathode and said first grid to provide a quartercycle transit time between said first and second grids, a half cycletransit time between said cathode and said first grid.

2. A space discharge system comprising a oathode to supply negativelycharged particles, an anode, first and second grids arranged insuccession in the order named between said cathode and anode, meansconnected between said cathode and said first grid to bias said firstgrid at a substantially constant initial positive potential with respectto said cathode, means connected between said cathode and said secondgrid to bias said second grid at a substantially constant potential inthe immediate neighborhood of the cathode potential to provide aretarding potential for negatively charged particles passing said firstgrid and approaching said second grid, means connected between saidcathode and said first grid to velocity vary charged particles in thespace between said cathode and said first grid whereby at least aportion of said particles are accelerated and thereby passed beyond saidsecond grid in groups in accordance with the action of the said velocityvarying means, and means connected between said second grid and saidanode to impress a substantially constant accelerating potential uponsaid anode with reference to said second grid to accelerate negativelycharged particles passing beyond said second grid thereby producing anoutput current flowing to the anode, the spacing between the cathode andthe first grid corresponding to a transit time substantially equal toone-half cycle at the operatin frequency to promoteefiicient velocityvariation.

3,. The system as in claim 2 in which the spacing between the first andsecond grids corresponds to a. transit time materially shorter than thatbetween the cathode and the first grid.

4. The system as in claim 2 in which the spacing between the first andsecond grids corresponds to a" transit time equal to substantiallyone-quarter cycle at the operating frequency.

PAUL L. HARTMAN.

REFERENCES CITED Number UNITED STATES PATENTS Name Date Thompson Dec. 3,1939 Hansen et a1 Dec. 31, 1940 Crawford May 10, 1938 Peterson May 21,1940 Gluyas, Jr Aug. 27, 1940 Varian et a1 June 10, 1941

